Inverted airfoil pylon for an aircraft

ABSTRACT

An aircraft including a wing and a pylon, wherein the pylon provides an airfoil inverted for an airfoil of the wing, and an improvement and method for improved flight dynamics for 20 and 30 Series LEARJET® is provided. The improvement includes an increased distance between a leading edge of a wing and an intake of an engine of the aircraft, which reduces drag and increases lift for improved flight dynamics of the aircraft. The inverted airfoil of the pylon negates an influence of the pylon on flight dynamics for improved overall flight dynamics of the aircraft. The method includes steps of removing an original engine from an original pylon, removing the original pylon from the fuselage of the aircraft, and mounting a new pylon in a new location adjacent to the fuselage, wherein the new location is aft of the original location.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/644,712 filed Dec. 22, 2006, entitled “An Inverted Airfoil Pylon ForAn Aircraft,” now U.S. Pat. No. 7,770,841, issued Aug. 10, 2010.

FIELD OF THE INVENTION

The claimed invention relates generally to the field of aviation andmore particularly, but not by way of limitation, to a method andapparatus for improved flight dynamics for an aircraft.

BACKGROUND

The optimization of flight dynamics for an aircraft is an important tasktypically undertaken by aeronautical engineers during the developmentand testing phases involved in bringing an aircraft to market. Followingdevelopment, testing, and certification phases of the Series 20LEARJET®, the aircraft was introduced to the market in 1964, and wasfollowed by the introduction of the Series 30 LEARJET® in 1974.

The handling characteristics of LEARJET® Series 20 and 30 yield aircraftthat is fairly complex to fly, which in the number of applicationsnecessitates the presence of two pilots during flight. The drag actingon aircraft, the available lift provided by the wings, and availablethrust provided by the engines each contribute to the aircraft'soperating efficiency and its ability to take off, land, and avoid astall condition during flight.

Two conditions known to be present in LEARJET® Series 20 and 30 aircraftfrom their introduction to the present are, their susceptibility ofencountering a stall condition, and the susceptibility of the aircraftto dip its nose when additional thrust is provided during flight.

Accordingly, there is a long felt need for improvements in the flightdynamics of LEARJET® Series 20 and 30 aircraft.

SUMMARY OF THE INVENTION

In accordance with a preferred embodiment, an aircraft includes at leasta fuselage supporting a wing, an engine for propelling said aircraft,and a pylon disposed between said engine and said fuselage and securingsaid engine to said fuselage, wherein said pylon provides an airfoilinverted from an airfoil of said wing.

In accordance with a preferred embodiment, an improvement for anaircraft selected from a group consisting of 20 Series and 30 SeriesLEARJET® that preferably includes at least increasing the horizontaldistance between the leading edge of a wing of the selected aircraft andan intake of an engine of the selected aircraft. The increasedhorizontal separation between the leading edge of the wing and theintake of the engine reduces drag and increases lift provided by thewing for improved flight dynamics of the selected aircraft. Theimprovement preferably further includes a pylon (for use in securing theengine to the fuselage) that provides an airfoil inverted in form from aform of an airfoil provided by the wing. The inverted airfoilneutralizes the effect of the pylon, relative to lift and drag, forimproved flight dynamic of the aircraft.

For the 20 Series LEARJET®, the preferred embodiment also preferablyincludes, the engine secured to the pylon such that a centerline passingthrough the engine is substantially parallel to a waterline of theaircraft. The substantially parallel alignment between the enginecenterline and said waterline reduces drag effecting said aircraftflight dynamics. An increased distance between the centerline of theengine and the waterline of the aircraft is preferably incorporatedwithin the improvement to increase lift provided by the wings of theaircraft, and an increased distance between the centerline of saidengine and a centerline of the fuselage is included in the improvementto reduce drag effecting the flight dynamics of the aircraft.

In accordance with an alternate preferred embodiment, a method ofimproving flight dynamics of an aircraft selected from a groupconsisting of (a 20 Series LEARJET® and a 30 Series LEARJET®) isprovided by steps that preferably include: removing an original enginefrom an original pylon of the aircraft; removing the original pylon froman original location adjacent a fuselage of the aircraft; and mounting anew pylon in a new location adjacent the fuselage, wherein the newlocation is located aft of said original location.

The alternate preferred embodiment preferably further includes the stepof mounting a new engine to the new pylon such that the distance betweena centerline of the new engine (which runs substantially parallel to thewaterline) and the waterline of the aircraft is greater than a distancebetween a central point along a centerline of the original engine andthe waterline. The alternate preferred embodiment also preferablyfurther includes the steps of: mounting the new engine on the new pylonsuch that a distance between a centerline of the new engine and acenterline of the fuselage is greater than a distance between acenterline of the original engine and the centerline of the fuselage;and covering the pylon with a skin, wherein the skin provides an airfoilinverted in shape relative to an airfoil shape provided by the wing ofsaid aircraft.

These and various other features and advantages, which characterizepreferred embodiments of the present invention, will be apparent fromreading the following detailed description in conjunction with reviewingthe associated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of prior art aircraft applicable to thepresent invention.

FIG. 2 provides a side elevational view of the prior art aircraft ofFIG. 1.

FIG. 3 provides a front elevational view of the prior art aircraft ofFIG. 1.

FIG. 4 is a top plan view of an aircraft of the present invention.

FIG. 5 provides a side elevational view of the aircraft of FIG. 4.

FIG. 6 provides a front elevational view of the aircraft of FIG. 4.

FIG. 7 shows a partial cross-sectional, side elevational view of a pylonand a wing of the aircraft of FIG. 4.

FIG. 8 is a diagram of a flowchart of a method of making the presentinvention.

DETAILED DESCRIPTION

Reference will now be made in detail to one or more examples of theinvention depicted in the accompanying figures. Each example is providedby way of explanation of the invention, and are not meant as, nor dothey represent, limitations of the invention. For example, featuresillustrated or described as part of one embodiment may be used withanother embodiment to yield still a different embodiment. Othermodifications and variations to the described embodiments are alsocontemplated and lie within the scope and spirit of the invention.

Referring to the drawings, to provide an enhanced understanding of thepresent invention, a reader is encouraged to view prior art FIGS. 1, 2,and 3 in concert while proceeding with reading this description of thepresent invention. Collectively, prior art FIGS. 1, 2, and 3 depictprior art 20 and 30 Series LEARJET® aircraft applicable for use with thepresent invention.

Prior art FIG. 1 is useful for presenting a plan view of both a priorart 20 Series LEARJET® aircraft and a prior art 30 Series LEARJET®(collectively prior art aircraft 10) found useful in practicing thepresent invention. Prior art FIG. 2 shows the prior art aircraft 10, inside elevational view, for a prior art 20 Series LEARJET® aircraft, andprior art FIG. 3 shows the front elevational view suitable for depictingeither the 20 or 30 Series prior art LEARJET® aircraft. Whencollectively viewing prior art FIGS. 1, 2, and 3, the reader's attentionis drawn to the location of the engines 12, relative to other sectionsand references of the aircraft, and in particular to the nacelle 13inclosing each engine 12.

Prior art FIG. 1 shows that engine inlets 14, of the engines 12, arecorrespondingly positioned at a predetermined distance 16 (of about 153centimeters) from a corresponding leading edge 18, of theircorresponding wings 20, and that each engine 12 is secured to a fuselage22, of the prior art aircraft 10 by a pylon 24. Prior art FIG. 1 furthershows centers of mass 26, of the engines 12, are correspondinglypositioned at a predetermined distance 28 (of about 111 centimeters)from a centerline 30, of the fuselage 22, of the prior art aircraft 10.

The prior art aircraft 10, of FIG. 2, depicts an orientation of theengine 12, for a prior art 20 Series LEARJET® aircraft relative to thefuselage 22 via the relationship between a centerline 32 of the engine12, and a waterline 34 of the prior art aircraft 10. In the prior art 20Series LEARJET®; the engine 12 is set at a predetermined pitch angle 36(of about 3°). That is, the engine 12 slopes from the engine inlet 14 toan engine outlet 38 at about a three-degree angle. Prior art FIG. 2 alsoshows the center of mass 26, of the engine 12, is positioned at apredetermined distance (of about 101 centimeters) from the waterline 34.

For both the 20 and 30 Series prior art LEARJET® shown by FIG. 3,nacelles 42 and fuselage skin 44 appear to abut one another. However, byreferring back to FIG. 1, it can be seen that the engines 12 are offsetfrom the fuselage 22 by the pylons 24. Nonetheless, FIG. 1 shows that aportion of the fuselage skin 44 and a portion of the nacelle 42 of theengine 40 lie coextensively with a cord line 46 (of FIG. 1).

The position of the engines 12 of the prior art aircraft 10 relative tothe wings 20 and the fuselage 22 has a direct bearing on the flightdynamics of prior art aircraft 10. The location of the engines 12,relative to the wings 20 creates a partial air dam between wings 20 andthe engines 12. The effect of this partial air dam is a disruption inthe fluid flow over the wings 20, which decrease the effectiveness ofthe wings 20. In other words, by partially disrupting the flow of fluidover the wing, the amount of available lift provided by the wing isdiminished. The diminished availability of lift provided by wings 20reduces the ability of prior art aircraft 10 to avoid stall conditionsduring flight.

The spacing of the engines 12, relative to the fuselage 22 also createsa partial air dam for fluid flowing between the fuselage 22 and theengines 12. The result of this disruption in fluid flow is an increasein the overall drag experienced by the prior art aircraft 10.

For the 20 Series prior art LEARJET®, the problem of reduced liftcapability of the wings 20 and increased drag created between thefuselage 22 in the engines 12 is exasperated by having the engines 12mounted at a 3° pitch, relative to the waterline 34. Mounting theengines 12 at a 3° pitch relative to the waterline 34 introducesadditional drag and difficult handling characteristics into the flightdynamics of the prior art aircraft 10. In addition to the increase indrag, the 3° pitch further affects the flight dynamics of the 20 SeriesLEARJET® by causing the nose of the prior art aircraft 10 to dip whenadditional throttle is applied to the engines 12 of the 20 SeriesLEARJET® during flight.

For ease in contrasting the present invention with the prior art, FIGS.4, 5, and 6 are provided to depict the present invention in viewscomparable to FIGS. 1, 2, and 3. Accordingly, viewing FIGS. 4, 5, and 6together will provide an enhanced understanding of the presentinvention. Collectively, FIGS. 4, 5, and 6 depict structural changesmade to the 20 and 30 Series LEARJET® aircraft to produce an improvedpresent inventive aircraft 100. FIG. 4 presents a plan view of aninventive aircraft 100 and is useful for showing a change in enginelocation between the prior art aircraft 10 (of FIG. 1) and the inventiveaircraft 100. FIG. 5 shows the inventive aircraft 100 in sideelevational view, which is useful in helping with an understanding of astructural change made to the 20 Series LEARJET® in arriving at thepresent inventive aircraft 100. FIG. 6 shows the front elevational viewof the inventive aircraft 100 suitable for depicting an additionalstructural change employed in arriving at the present inventive aircraft100. When collectively viewing FIGS. 4, 5, and 6, the reader's attentionis drawn to the location of the engines 102, relative to other sectionsand references of the inventive aircraft 100.

In a preferred embodiment shown by FIG. 4, engine inlets 104 of theengines 102, are preferably positioned at a distance 106 (of about 194centimeters) from corresponding leading edges 108 of corresponding wings110. Each engine 102 is preferably secured to a fuselage 112 by a pylon114. FIG. 4 further shows centers of mass 116, of the engines 102, arepreferably correspondingly positioned at a distance 118 (of about 121.5centimeters) from a centerline 120, of the fuselage 112 of the inventiveaircraft 100.

The inventive aircraft 100 of FIG. 5 shows an orientation of the engine102 (for an inventive aircraft 100 based on a 20 Series LEARJET®)relative to a centerline 122 of the engine 102, and a waterline 124 ofthe inventive aircraft 100. In the 20 Series LEARJET® prior art aircraft10 (of FIG. 2), the engine 12 is set at a downwardly sloping 3° pitch.In a preferred embodiment shown by FIG. 5, the relationship between thecenterline 122 and the waterline 124 shows an absence of a pitch, i.e.,the centerline 122 lies substantially parallel to the waterline 124.FIG. 5 also shows the center of mass 116, of the engine 102, ispositioned at a selected distance 126 (of about 109 centimeters) fromthe waterline 124.

In a preferred embodiment of the inventive aircraft 100 shown by FIG. 6,nacelles 128 are offset from a fuselage skin 130 such that a portion ofthe pylons 114 are brought into view when viewing the inventive aircraft100 from a front elevational perspective. By referring back to FIG. 4,it can be seen that the engines 102 are offset from the fuselage 112 bythe pylons 114 at a distance sufficient to assure that the nacelle 128does not lie coextensively with a cord line 132, which lies tangent tothe fuselage skin 130.

The position of the engines 102 of the inventive aircraft 100 relativeto the wings 110 and the fuselage 112 has a direct bearing on improvedflight dynamics of the inventive aircraft 100, when compared to theflight dynamics of the prior art aircraft 10 (of FIGS. 1-3). Thelocation of the engines 102, relative to the wings 110 alleviates thepartial air dam present between wings 20 in the engines 12 of the priorart aircraft 10. By alleviating the air dam, the amount of availablelift provided by the wings 110 is greatly enhanced. The spacing of theengines 102, relative to the fuselage 112 removes from the inventiveaircraft 100 the partial air dam developed between the fuselage 22 inthe engines 12 of prior art aircraft 10, which decreases the overalldrag experienced by the inventive aircraft 100.

For the inventive aircraft 100 based on the 20 Series LEARJET®, removingthe 3° pitch of the engines 12, relative to the waterline 34 on theprior art aircraft 10 (of FIG. 2), alleviates the drag created by the 3°pitch, and the tendency of the nose to dip during in flightaccelerations.

In a preferred embodiment, the following dimensional changes for enginelocation have been found useful in providing the inventive aircraft 100based on either the 20 or 30 Series LEARJET®. Those dimensional changesfor engine location include positioning the engines 102: about 41centimeters further back from the leading edge 108 of the wing 110 at apoint adjacent the fuselage 112; about 8 centimeters further up from thewaterline 124; and about 10.2 centimeters further out from the fuselagecenterline 120. It has been found that these improvements dramaticallyimprove the flight dynamics of the inventive aircraft 100, relative tothe flight dynamics of the prior art aircraft 10. The improvementincludes a greatly enhanced ability to avoid stall conditions during inflight maneuvers.

FIG. 7 shows that in a preferred embodiment of the present invention, anairfoil 134 is provided by a skin 136 of the pylon 114. Preferably, theshape of the airfoil 134 is inverted in form from the shape of anairfoil 138 provided by the wing 110. By presenting the airfoil 134 toan air stream in an orientation inverted from the airfoil 138 of thewing 110, an influence of the pylon 114 on the flight dynamics of theinventive aircraft 100 is neutralized. That is to say, by providing aninverted airfoil 134 covering the pylon 114, the pylon 114 neither addsto the drag nor detracts from the lift of the inventive aircraft 100.The shape of the airfoil of the pylon, i.e., inverted from the shape ofthe airfoil of the wing, has removed the pylon as a structural componenteffecting the aerodynamics of the aircraft.

Turning to FIG. 8, the flow chart 200 depicts a process of forming aninventive aircraft (such as 100). The method commences at start step 202and proceeds to process step 204 with the removal of an engine (such as12). At process step 206, a pylon (such as 24) is removed from afuselage (such as 22) of the inventive aircraft. Following the removalof the pylon from the fuselage; providing a portion of fuselage skin(such as 44) to cover the portion of the fuselage left open by removalof the pylon; and removing a portion of fuselage skin from the airframein preparation for mounting a new pylon (such as 114), the new pylon issecured to the fuselage at process step 208.

At process step 210, a new engine (such as 102) is mounted to the newpylon. At process step 212, the new pylon is covered with a skin (suchas 136) to provide an airfoil (such as 134) and the process concludes atend process step 214.

It is to be understood that even though numerous characteristics andadvantages of various embodiments of the present invention have been setforth in the foregoing description, together with details of thestructure and function thereof, this detailed description isillustrative only, and changes may be made in detail, especially inmatters of structure and arrangement of parts within the principles ofthe invention to the full extent indicated by the broad general meaningof the terms in which the appended claims are expressed. For example,the particular elements may vary depending on the particular applicationfor a select engine, while maintaining the same functionality withoutdeparting from the spirit and scope of the invention.

1. An aircraft comprising: a fuselage supporting a main wing; an enginefor propelling said aircraft; and a pylon disposed between said engineand said fuselage and directly securing said engine to said fuselage,wherein said pylon provides a fixed, flap free airfoil inverted in shaperelative to an airfoil shape provided by said main wing.
 2. The aircraftof claim 1, in which said engine includes a nacelle, and wherein saidpylon is configured to negate formation of a shock wave between saidfuselage and said nacelle, and wherein said fixed, flap free airfoilinverted in shape relative to the airfoil shape provided by said mainwing negates said pylon as a structural component affecting theaerodynamics of said aircraft.
 3. The aircraft of claim 1, in which saidengine includes a nacelle, and wherein said nacelle is positioned apredetermined distance from a leading edge of said main wing to negateformation of a shock wave between said main wing and said nacelle. 4.The aircraft of claim 1, in which said engine is secured to said pylonsuch that a centerline passing through said engine is substantiallyparallel to a waterline of said aircraft, said substantially parallelalignment between said engine centerline and said waterline reduces dragaffecting said aircraft flight dynamics.
 5. The aircraft of claim 1, inwhich said engine is secured to said pylon such that a centerlinepassing through said engine is substantially parallel to a waterline ofsaid aircraft, said substantially parallel alignment between said enginecenterline and said waterline increases lift provided by said main wingof said aircraft.
 6. The aircraft of claim 1, in which a distancebetween a centerline of said engine and a centerline of said fuselage isselected to reduce drag affecting said aircraft.